Alternating-current arc-welding system



W. A. HALL. ALTERNATING CURRENT AIIC WELDING SYSTENI.

APPLICATION FILED SEPT. 23| T918.

Patented Jan.. 49 INET...

UNiTED STATES PAT-ENT OFFICE.

WILLIAM A. HALL,

OF YONKERS, NEW YORK, ASSIGNOR OF ONE-HALF T CHARLES H. FLORANDIN', 0FWESTFIELD, NEW JERSEY.

ALTERNATING-CURRENT ARC-WELDING SYSTEM.

n arc systems as referred to above, it is desirable that a comparativelyhigh voltage be impressed upon the electrodes on `open circuit so that ahigh voltage will exist at the instant of striking the arc. After thearc has been struck and the working current is owing, it is desirablethat this Voltage should be reduced. In other words a high startingvoltage and a low working voltage upon the electrodes, is desirable. Itis further desirable that this regulation in voltage shall be auto-maticand also that it shall be accomplished without the movement of parts.Accordingly attempts have been made to effect these changes 1n voltageon alternating current systems by means of transforming apparatuswherein there was a shifting of the relative positions of the pathsofthe flux and the windings according to the secondary current in thetransformer. lIt has been found, however, in all prior devices that theautomatic shifting of the flux paths with relation to the transformerwindings, has occasioned such confusion in the distribution of the flux,that the power factor has been low.

It is the main obj ect of the present invention to provide apparatuswhereby automatic `regulation of the voltage as above indicated by meansof transforming apparatus without moving partsand in response to thesecondary current is effected but with an improved power factor.

Other and ancillary objects of the invention will appear hereinafter.

In the accompanying drawings which illustrate the invention- Figure 1 isa View of a shell type transformer adapted for use in a system embodyingthe invention, the transformer core be- Specication of Letters Patent.

Patented Jan. 4, 1921.

Application tiled September 23, 1918. ,Serial No. 255,347.

Fig. 2 is a section on the line 2--2 of' Fig. 1;

Pig. 3 is a diagram of connections of an arc welding s stem including atransformer as shown in *igs. 1 and 2, and embodying the invention, and

Fig. 4 is a view similar to Fig. 2 but showing the 4distribution of iuxunder different conditions.

Referring to the drawings, the transformer employed, comprises alaminated core 1. Within this core are slots as 2 and 3 and interiorlyof the slots 2 and 3 are other slots 4 and 5. In the slots 2 and 3 areplaced the primary winding 6 and the secondary winding section 7, whilein the slots 4 and 5 are placed another secondary winding section 8 andan adjusting winding 9. It will be seen that the slots 4 and 5 and theircontained windings, are symmetrically arranged with relation to theslots 2 and 3 and their contained windings. The windings 6 and 7, itwill be observed, embrace the sections 10, 11 and 12 of the core, whilethe windings 8 and 9 encircle the section 11 only.

The connection of the windings may be best understood by reference tothe diagram of connections of Fig. 3. Suitable supply leads 13 and 14are connected to any suitable source of alternating current. Connectedacross these leads 13 and 14 is the transformer primary winding 6. Thesecondary winding section 7 is connected in series with the secondarywinding section 8, the terminals of these windings being connected withvthe electrodes 15 and 16 of the arc for acting upon the work. Usuallyone of these electrodes as 16, is the work itself, while the other as 15is manipulated by the operator. The adjusting winding 9 is connectedacross the leads 13 and 14 in series with an adjustable non-inductiveresistance 17, whereby the current may be varied in the winding 9.

With the electrodes 15 and 16 separated and with no arc between them,that is, the secondary circuit being open, the flux passing through theinterior of the primary coil 6 will pass through the core sections 10,11 and 12. This will induce electromotive force in the secondary windingor coil7, while that portion of the flux which passes through the coresection 11, will thread the interior of the secondary coil 8 and inducea corresponding amount of electromotive force therein. The distributionof flux is as indicated by the lines a of Fig. 2. The secondary windings7 and 8 being connected in series, these electromotive forces will beadded together so that the potential at the terminals of the secondarysections will be the sum of the electromotive forces generated in them.Consequently the voltage impressed upon the electrodes 15 and 16 on opencircuit and u on striking the arc, will be the sum of the e ectromotiveforces generated in the coils 7 and 8 as above referred to.V

When, however, the archas been struck and current flows in the secondarycircuit, thel magnetomotive forces due to the secondary ampere turns,will oppose the magnetomotive forces due to the primary winding, as iswell understood. The wlnding section 8 of the secondary is preferablyarranged so that at the normal working load of the secondary circuit,the primary magnetomotive forces tending to force flux through the coresection 11 will be neutralized by the .magnetomotive forces due to theampere turns of the secondary winding 8. The flux distribution is thenas indicated by the lines b of Fig. 4f. In order that this adjustment ofneutrality may be readily brought about where it is impracticable toeffect this by the secondary coils alone, the adjusting winding 9 issupplied. The ampere turns of this' winding may be suitable to effectthe desired regulation by means of the variable resistance 17 which 'ispreferably non-inductive so as to avoid shifting of the phase of currentin the winding 9. Where such shifting exists the currents in' thewindings 8 and 9 and consequently their magnetomotive forces would beout of step and would not therefore be so Well adapted to theneutralization above referred to. 1

With the magnetomotive forces acting upon the core section .11neutralized, there will be no flux through this core section, and,

there being no flux threading this core section, substantially noelectromotive force will be induced in the secondary coil section 8. Theelectromotive force impressed on the arc electrode therefore, will besubstantially that generated in the secondary winding section 7. It willnow be seen that there will be a high electromotive force, that due tothe electromotive forces of the windings 7 and 8, impressed upon theelectrodes 15 and 16 on open circuit and at the instant the arc isstruck, while the voltage impressed on the electrodes while normalworking current is flowing will be substantially that generated in thesection 7 and is therefore lower than the open circuit or arc startingvoltage.

of the electromotive force otherwise generated in the secondary. windingsection 8, is effected wlthout producing such a -disturbing influence.upon the relations of the primary winding 6 and the secondary windingsection 7, the core sections 10 and 12 prbviding ample paths for theflux when the section 11 is not used as such path. Also sincesubstantially no flux threads lthe section 8, it will have'no selfinduction and as 1t 1s in series in the secondary circuit this verymaterially raises the power factor. It is desirable that the windingsection 8 be symmetrically arranged with relation to the windings 6 and7 so that the magnetomotive forces may be balanced. While the inventionhas been illustrated in what is considered its best embodiment, 1t mayhave other embodiments without departing from its spirit and is nottherefore limited to the structure shown in the drawing.

What I claim isf 1; A shell type transformer having a core, a primarywinding and a sectional secondary w1nd1ng, one of said sections beingarranged interiorly of the other and encircling different sections ofthe core.

2. 'A shell type transformer having a core, a primary winding and asectional secondary wlndlng, one of said sections being arrangedinteriorly of the other and encircling different sections of the-core,the interiorly arranged secondary section substantially neutralizing themagnetomotive forces acting upon the core section encircled by it.

3. A shell type transformer having a core, a primary winding and asectional secondary winding, one of said sections being arrangedinteriorly of the other-and encircling different sections of the core,and auxiliary means for adjusting the magnetomotive forces acting uponthe core section encircled by one of the secondary winding sections. l4. A shell type transformer having a core,

a primary wlnding and a sectional secondary winding, one of saidsections being arranged interlorly of the other and encircling differentsections of the core, the .interiorly arranged secondary sectionreducing the flux in the coresection encircled by it, occasioned by theprimary magnetomotive force.

5. A shell type transformer having a core, a primary winding and asectional secondary winding, one of said sections being arrangedinteriorly of the other and encircling different sections of the core,the interiorly arranged secondary section being symmetrical withrelation to the other secondary section.

6. A transformer having a core, a primary Winding and a sectionalsecondary Winding, the secondary sections encircling different sectionsof the core, a secondary section substantially neutralizing the primarymagnetomotive forces acting upon the core sections encircled by it.

7. A transformer having a core, a primary winding and a sectionalsecondary winding, the secondary sections encircling different sectionsof the core, and auxiliary means for adjusting the magnetomotive forces,acting upon a core section encircled by one of the secondary Windingsections.

8. A transformer having a core, a primary Winding and a sectionalsecondary Winding, the secondary Winding sections being connected inseries and encircling different sections of the core, one of saidsecondary sections at a predetermined load substantially neutralizingthe magnetomotive forces acting upon the core section encircled by it.

In testimony whereof I have signed this specication this 17th day ofSeptember,

WILLIAM A. HALL.

